1. Field of the Invention
The present invention relates to the improvement of paper money identification devices which determine the authenticity of inserted paper money.
2. Description of the Related Art
Paper money identification devices which identify the genuineness of inserted paper money are generally finished in paper money processing devices for determining the genuineness of inserted paper money, storing genuine notes in a stacker and rejecting non-genuine notes.
Such paper money identification devices are generally constituted by an optical sensor comprising light-emitting and light-receiving elements (light-emitting and light receiving diodes) which identify the shade variation of the paper money, and a magnetic sensor comprising a magnetic head for detecting the magnetism of the paper money. These sensors are arranged so as to be exposed facing the paper money transport path of the paper money processing device.
In such paper money identification devices which comprise an optical sensor and a magnetic sensor, when an inserted paper money is passed along the paper money transport path, the optical sensor identifies the shade variation of the inserted paper money, and the magnetic sensor detects the magnetism of the paper money.
Threshold values are respectively established beforehand for the detection values of these sensors. When the detection values of an inserted paper money as detected by the optical sensor and magnetic sensor fall outside the threshold values, the paper money will be judged xe2x80x9cnot genuinexe2x80x9d and will be returned via the paper money insertion port. On the other hand, when the respective detection values of the inserted paper money as detected by the optical sensor and magnetic sensor fall within the threshold values, the paper money will be judged xe2x80x9cgenuinexe2x80x9d, and the paper money then transported further downstream on the paper money transport path and stored in the stacker.
In recent years, in order to reduce weight, lower costs and other reasons, the paper money transport path has been composed of a chute generally formed from a plastic or other synthetic resin.
As described above, the paper money identification devices employ the optical sensor. The optical sensor has a problem that, if any dust or dirt adheres to the optical sensor, its sensitivity will suffer and accurate detection of the paper money shade variation will become impossible.
On the other hand, as mentioned above, the chute, which constitutes the paper money transport path on which the optical sensor is disposed, is usually formed from a plastic or other synthetic resin. These materials can readily generate an electrostatic charge thereon. Further, when a paper money passes along this chute, the friction between the chute and the paper money can readily strengthen the electrostatic charge in this area.
Therefore, when dust or dirt having entered through the paper money insertion port, or paper money to which such dust and dirt have adhered, passes through the chute made of a synthetic resin, the electrostatic charge generated on the chute will cause the dust and dirt to become attached to the chute. Should the dust and dirt become attached to the optical sensor which is exposed on the path, as noted above, its sensitivity will suffer and accurate detection of the paper money shade variation will become impossible.
With the foregoing issues in view, it is an object of the present invention to provide a paper money identification device which prevents to as great an extent as possible the adhering of dust and dirt to the optical sensor.
In order to achieve the aforementioned object, in a first paper money identification device according to the present invention, which detects shade variation of a paper money that passes along a paper money transport path by means of an optical sensor to judge authenticity of the paper money, a surface of the optical sensor facing on the paper money transport path is covered by a transparent antistatic cover.
Moreover, in a second paper money identification device according to the present invention, which detects shade variation of a paper money which passes along a chute serving as a paper money transport path by means of an optical sensor disposed at the chute to judge authenticity of the paper money, the chute is formed from an antistatic synthetic resin.
Moreover, in a third paper money identification device according to the present invention, which detects shade variation of a paper money which passes along a chute serving as a paper money transport pa th by means of an optical sensor to judge authenticity of the paper money, the chute is subjected to an antistatic coating treatment, and the optical sensor is disposed on the chute that has been subjected to the antistatic coating treatment.